1. Field of the Invention
The invention relates to the improvement of sanitization techniques used during the processing of food products, more specifically, it relates to the use of liquid nitrogen and an additive for treating food items in an interior of food processing equipment.
2. Description of the Related Art
It's typical for food companies to add additives during processing steps in order to improve the safety, quality and texture of food products. The list of additives for a specific use and approved limits may be any one that is listed as GRAS (Generally Recognized as Safe) by the United States Food & Drug Administration. The additives are classified based on their intended use in food (or) type of chemical compound such as antimicrobial, preservative, colorant, flavor, antioxidants, reducing agents, antifungal agents, antibiotics, oxidative and reducing agents, pH agents, etc. For example, preservatives are static agents that are added to food to inhibit microbial growth and must be non-toxic and safe for human consumption. Salts of organic acids (propionate, sorbate, benzoate and lactate) are preservatives that act by increasing the proton concentration of the cytoplasm of many microbes. In general, antimicrobials and preservatives penetrate the cell membranes and disrupt ATP synthesis in respiring microorganisms. These effects in cellular membrane cause slow growth and negatively impact cell energy. Likewise, each additive has a specific use for addition to food products.
Food safety problems not only originate in the food product itself (e.g., raw ingredients), but also from the environment surrounding the food product. A food product is susceptible to microbial contamination during the processing steps and after the terminal heating process. Operations with poor sanitation in the packing environment can significantly increase the risk of contaminating a food product. For example, pathogenic microorganisms may be found on the floors and in the drains in the packing facility and on the surfaces of sorting, grading, and packing equipment. Without good sanitary practices, any of these surfaces that come in contact a food product could be a potential source of microbial contamination.
According to at least one estimate, post/cross contamination from either environment or food contact surfaces is implicated in up to 30% of food poisoning cases. Post/cross contamination also increases the microbial load in finished products, shortening shelf-life and becoming a visual deterrent of quality. As such, the finished product can serve as a carrier of cross-contamination leading to economic losses, as well as health and survival issues involving consumers. For example, Listeria spp is an environmental air-borne pathogen causing listeriosis that can contaminate food products during processing. According to the Center for Disease Control, there were 1850 cases of listeriosis in 1998, including 435 deaths from this disease. Effective methods using sanitizers/disinfectants are crucial to minimize and prevent microbial contamination of foods.
Effective sanitation of food or other items depends on the combination of what is to be sanitized and the sanitation process type. Not all of the currently available technologies can deliver an effective reduction of microorganisms and at the same time prevent product or environmental degradation. It is well known in the art to cool products, such as foods, during processing with some type of refrigerant to slow down the growth of unwanted microbes and enzymatic reactions in foods. For instance, the shelf life and quality of food products are improved by processing, transporting, and storing under refrigerated conditions.
Cooling agents, such as liquid nitrogen, are agents that can be used as expendable refrigerants. Water ice is a traditional expendable refrigerant, but has the disadvantage of converting to water after the ice melts. Liquid nitrogen vaporizes upon absorbing heat from its environment (such as an interior of food processing equipment). The cold temperature of liquid nitrogen and the fact that it leaves no residue like water ice makes it an excellent refrigerant in some applications. For example, when rapid cooling of food products is desired, it can be mixed with liquid nitrogen.
There are many applications that use liquid nitrogen as the coolant to chill and freeze food products (beef, poultry, seafood, etc.) during processing steps. Liquid nitrogen can be injected into various types of equipment involved in food processing such as tumblers, mixers, freezing tunnels, and blenders to effectively refrigerate the equipment for extended periods of time.
Although refrigeration can retard microbial growth, such treatment does not necessarily kill bacteria. Accordingly, microorganisms can still survive through refrigeration, and worse, some microorganisms can still grow and produce harmful substances during refrigerated storage. It is desirable to sanitize equipment and processed foods with a combination of cooling properties found in cooling agents and antimicrobial capabilities of sanitizing agents. It is further desirable to expose the equipment or food product to a cooling agent and sanitizing agent simultaneously.
We have previously described a method for mixing an additive with liquid carbon dioxide for treatment of food items in a food processing equipment. However, when CO2 prices rise to unacceptably high levels or if CO2 availability is low, implementation of that method can be inhibited.
Therefore, there remains a need to provide an improved method for treating and cooling food items that does not rely upon CO2.